surgical instruments market

Maintenance » Instruments Problems

Spots and Stains  
In nearly all cases these problems are the result of minerals being deposited upon the surface of the instruments which appear as brown, blue... colors etc. Often, yellow-brown, to dark-brown blister-like spots show on sterilized instruments are mistaken as rust. In most cases, such residue can contain high degrees on chlorides which then lead to chloride induced pitting on parts made of stainless steel if the spots are not removed immediately.
So, adhering to proper technique during cleaning and sterilizing procedures will prevent most staining oc¬currences. The following table summarizes the causes and treatments of most common spots and stains.





Brown Stains

Copper Coating or Platting

Detergents containing polyphosphates

Use Neutral Detergent or check the quantities used.

Blue Stains

Residue Deposits

Use of cold sterilization techniques(Old sterilizing solutions)

  • Change baths after each use
  • Rinse instruments immediately after use in distilled or de-mineralized water.

Black Stains

Caustic Reaction

  • Detergents containing ammonia
  • amine deposits traced to the steam in the autoclaves
  • Use Neutral Detergent
  • follow steam line cleaning procedures with a cycle of distilled water to remove all traces of amines

Bluish-Blackish Stains

Metallic Coating or Platting

Metals of different types have been sterilized together e.g; stainless steel with Silver / Chrome / etc.

Sterilize only the similar metal instruments together

Light or Dark Spots

Metal Deposits

  • In flushing water or steam there are iron, copper, manganese etc: are present
  • instrument wraps
  • Use distilled or de-mineralized water
  • detergents are thoroughly rinsed out

Rust Deposits


residual organic matter or mineral deposits

use of distilled or demineralized water

Several Colors

Excess Heat (Chromatic Oxide)

The autoclave is not operating properly or
has been set to very high temperature (This can cause metal to lose some of its properties such as strength and hardness etc, etc.)

Correct the autoclave temperature

The use of distilled water, careful preliminary cleaning, using neutralized pH solutions, following manufacturer's instructions, visual inspection, will all help to keep instruments performing accurately and cosmetically free of troublesome stains.  
Corrosion is the disintegration of an engineered material into its constituent atoms due to chemical reactions with its surroundings. In case of surgical instruments any kind of corrosion can only occur due to inductions of water, aque¬ous solutions or steam.  
How corrosion occurs  
Two factors affecting corrosion resistance, the chromium and carbon contents of stainless steel. In general, the more chromium present in the alloy, the more resistant it is to the cor¬rosion. Carbon reduces the corrosion resistant effect of chromium, but it is necessary to produce hardness. In order to minimize corrosion of these harden able stainless steel alloys, the instrument will have passed through two processing steps which increase its re¬sistance to corrosion; Passivation and Polishing (review the production process).  
Kinds Of Corrosion  
The following table describes the most important kinds of corrosion and their effects, in the sequence of their frequency of appearance.

Corrosion Type




Pitting corrosion

surface holes, rust and finally
destroy the instruments

active chlorides (chloride induced pitting) or halide ions
other electrochemical causes

Clean instruments immediately after use in distilled water

Stress Corrosion

cracking at the joints

incorrect handling
chloride involved in water

only close the ?rst ratchet during sterilization
use distilled water

Fretting and crevice corrosion

  • metallic abrasion in joints
  • hinders smooth action of the instrument
  • rust blisters in the crevices

*chemical or mechanical destruction of the natural passive coating of the high quality steel.
*lack of sufficient lubrication

  • only close the ?rst ratchet during sterilization
  • use distilled water
  • lubricate instruments

Contact corrosion

rust blisters

Metallic contact of instruments and unfavorable cleaning and rinsing conditions,
e.g. tap water containing chlorides or contact with non stainless steel goods, such as needles, cutters, etc

Manual cleaning is preferable than machine cleaning
Avoid contacts with non stainless steel goods

Surface corrosion

instrument rust

chemical or other electrochemical in?uences

Avoid chemical or other electrochemical in?uences

resultant corrosion

A-Transferred rust
B- extraneous rust

A-Transfer of rust particles from one instrument to another during disinfection, cleaning or sterilizing
B- deposit of transport rust particles on the inside of the sterilizing chamber, on the packing, on instrument surfaces.

A-separate corroded instruments 
B-Clean both sterilizer steam pipes and inside of the sterilizing chamber

In order to reduce corrosion, instruments must be thoroughly cleaned and dried, and they must not be given prolonged exposure to sterilizing solutions. When corrosion does occur in stainless steel instruments, it is usually of super?cial nature. This surface corrosion may be removed by soaking in a solution of alcohol and ammonia or by repolishing by the manufacturer.

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